Monomer-plasticized elastomers and process for producing same

ABSTRACT

Elastomers are plasticized with a polymerizable monomer, in homogeneous admixture therewith, by adding the monomer to a latex of the elastomer, free of polymerization initiator, followed by coagulation of the monomer and polymer solids. The coagulated solids recovered from the latex may be compounded with a polymerization initiator for the monomer and a vulcanizing agent for the polymer and, optionally, an inorganic filler, and shaped into the desired product form. Polymerization of the polymer and vulcanization of the elastomeric polymer are initiated after shaping.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to homogeneous monomer-containing vulcanizablecompositions derived from rubber latices, to processes for theirpreparation, and to covers of the vulcanized compositions for rolls ofthe types employed in the papermaking and textile industries.

2. Description of the Prior Art

Rolls having a metallic core with a relatively hard elastomeric coveringhave long been used in machinery for the making, handling and processingof lengths of paper and textiles. Where high roll pressures areemployed, deformation of the elastomeric covering generates heat whichmay elevate the temperature within the cover to temperatures as high asabout 200° F. Service under such conditions of pressure and temperaturewill eventually lead to fatigue problems often seen as separation of thecover from the core and as cracks at the surface of the elastomer cover.Fillers and fiber reinforcement represent the conventional approaches tocontrolling fatigue in the roll cover.

In addition to resistance to fatigue such roll covers should have highabrasion resistance. Abrasion is a problem, for example, in the presssection of papermaking machinery where rubber covered rolls press thewet paper web, which web typically contains abrasives inadvertentlyintroduced with the pulp as well as abrasives intentionally added to thepaper stock as fillers. Copolymers of butadiene and acrylonitirle arenoted for their hardness and have been used in many applications wherehigh resistance to abrasion is required.

The abrasion resistance of rubbers generally increases with increasingmolecular weight. However, viscosity of the unvulcanized rubber alsoincreases with increase in molecular weight. Accordingly, inconventional practice a plasticizer ("extending oil") is added to theunvulcanized rubber to lower its viscosity and to increase itsworkability to a point suitable for extrusion or other processing. Inthe case of acrylonitrile/butadiene (nitrile) rubbers, however, theaddition of plasticizers has proven difficult in practice.

U.S. Pat. No. 4,143,092 and Encyclopedia of Polymer Science andTechnology (Vol. 2, p. 705) note thate only a limited number of"extending oils" or "plasticizers" are compatible withacrylonitrile/butadiene rubber, the majority of conventionalplasticizers tending to ooze from the surface of the rubber as if from afine-pored sponge. The patent further teaches that ester plasticizers,such as dioctyl phthalate, dibutyl phthalate dioctyl adipate, etc.,while compatible with the rubber, are susceptible to leaching by inkvehicles and roll cleaning compounds. Similar leaching of theconventional ester plasticizers has now been noted to occur inapplications in the papermaking and textile industries. For example, inthe conventional papermaking processing bleaching agents and defoamersare commonly added to the paper stock. These agents as well as coatingagents, waterproofing agents, etc., used to treat the formed paper areall potential leachants. Additionally, textile and papermaking rolls areconventionally cleaned with aromatic compounds such as kerosene whichare also solvents for many conventional plasticizers.

Kent et al in U.S. Pat. No. 3,528,936 and Cowperthwaite et al in U.S.Pat. No. 3,751,378 recognize that high molecular weight polymers ofbutadiene, etc., may be plasticized by addition of certain polyestermonomers. Both patents teach admixture of the monomer and polymertogether with an inorganic filler and other ingredients on an open millor in an internal mixer, i.e., "dry" blending with a filler. In theseprior art dry blending processes, a homogeneous admixture of monomer inpolymer is impossible without the inorganic filler which serves as acarrier for the monomer and as a dispersant.

SUMMARY OF THE INVENTION

It has now been discovered that an elastomeric polymer may beplasticized with polymerizable monomer, in homogeneous admixturetherewith, by adding the monomer to a latex of the polymer andcoagulating the solids to form the homogeneous admixture. It has beenfurther discovered that the plasticized elastomeric compositions soproduced have more uniform consistency, i.e., a greater degree ofhomogeneity, than do similar compositions prepared by dry blending thepolymer and monomer utilizing an inorganic filler to introduce themonomer into the polymer.

More specifically, the present invention provides a monomer-plasticized,non-crosslinked elastomeric composition in the form of a homogeneousadmixture of elastomeric polymer and a polyfunctional polymerizablemonomer, free of inorganic filler. These non-crosslinked compositionshave low viscosity with little or no cold-flow. The plasticizedelastomeric compositions may be produced by admixing 5.0-100 parts byweight of the polymerizable monomer with 100 parts by weight (solidsbasis) of a latex of the elastomeric polymer and then coagulating thesolids in the latex, inclusive of the monomer and polymer, in aconventional manner. The coagulated solids are separated from theaqueous phase of the latex to provide the homogeneous elastomericcomposition of the invention. The admixing, coagulating and recoverysteps are all conducted in the absence of a polymerization initiator,catalyst, polymerizing radiation, etc., and under conditions wherebysubstantially no grafting or crosslinking of the elstomer occurs andsubstantially no polymerization of th monomer occurs. Accordingly, thesolids admixture recovered from suspension by coagulating consistsessentially of a completely homogeneous admixture of (1) substantiallyungrafted, uncrosslinked elastomer and (2) unpolymerized monomer.

The plasticizing effect of the monomer becomes evident upon addition of5-10 parts by weight (in some cases more) of the monomer to 100 parts byweight of the elastomer, depending on the nature of the monomer and thatof the elastomer. A marked effect on cold-flow characteristics may beseen upon admixture of as little as 0.5 parts by weight monomer to 100parts by weight polymer.

A further aspect of the invention involves compounding thenon-crosslinked elastomeric composition, containing the polymer andmonomer in homogeneous admixture, with a vulcanizing agent for theelastomeric polymer and a polymerization initiator for thepolyfunctional monomer. Normally, the same free radical producingcompound is employed as both the vulcanizing agent and thepolymerization initiator. For the manufacture of rubber-covered rolls,the aforementioned ingredients are further compounded with an inorganicfiller and the roll core is covered with the compound composition in aconventional manner and then heated to effect polymerization of themonomer and vulcanization of the elastomeric polymer. The presentinvention is founded, in part, on recognition that the conventionalprior art admixtures, upon vulcanization, provide products characterizedby a two-phase morphology in which areas of homopolymer (derived fromthe polyfunctional monomer) are dispersed through the copolymer. Thistwo-phase morphology is believed to be attributable to the competingaffinities of monomer to filler, polymer to filler and monomer topolymer. It has been discovered that fatigue problems seen in thevulcanized products, e.g., surface cracking of roll covers, areattributable in large measure to the presence of the homopolymer phaseand to its non-uniform distribution through the rubber phase. Due to thedifference between the glass transition temperatures of the homopolymerand rubber phases, the coefficients of linear expansion of the two phasediffer, resulting in stresses within areas of high homopolymerconcentration in the vulcanized products. It has been further discoveredthat the degree of consistency necessary to avoid such fatigue problemsin the vulcanized product are obtained only with great difficulty, if atall, using the conventional techniques for compounding, i.e., dryblending. In contrast, the present invention provides a homogeneoussingle-phase product.

An important aspect of the invention is that polymerization of themonomer should not be initiated prior to shaping. Accordingly, theadmixture recovered by coagulation will be free of any polymerizationinitiator for the monomer. If polymerization of the monomer, grafting orcross-linking is initiated prior to shaping, the objectives of thepresent invention of providing a high molecular weight polymer,plasticized to provide a highly workable vulcanizable composition, willbe frustrated.

Polyfunctional monomers, especially trifunctional monomers, arepreferred for use in the present invention because of their lower vaporpressure and volatility and because they yield vulcanized products ofhigher hardness and rigidity. The preferred compositions are copolymersof butadiene and acrylonitrile plasticized with an acrylic ormethacrylic acid ester of a polyol.

The term "high molecular weight" as used herein to describe theelastomeric polymers has reference to a number average molecular weightof about 20,000 to 70,000 for synthetic elastomers and higher fornatural rubbers.

The term "latex" as used herein is not limited to aqueous dispersions ofthe elastomeric polymer but, rather, is intended to include similardispersions in other liquid mediums.

Accordingly, it is an object of the present invention to produce anunvulcanized synthetic rubber composition of high molecular weight yethaving sufficiently low viscosity and good processability that it issuitable for the production of products such as roll covers by utilizingconventional rubber mixing equipment such as mills and extruders.

It is a further object of the invention to provide such an unvulcanizedcomposition of high molecular weight admixed with the viscosity reducingextender or plasticizer which is completely homogeneous and therebyyields a finished product free of areas possessing differingcoefficients of linear expansion, i.e., a single-phase product.

It is yet a further object of the invention to provide such a rubberadmixture wherein the plasticizer extender is of a nature which is fullycompatible with the synthetic rubber yet resists extraction from thefinished product by solvents to which it might be exposed in variousapplications in the papermaking and textile industries.

Yet a further object of the invention is to provide a rubber cover for aroll which exhibits a high degree of abrasion resistance yet maintains asmooth surface over extended periods of service.

Yet a further object of the invention is to provide a cured rubber coverwhich maintains a smooth surface by resistance to deformation and/orcracking due to fatigue and/or hardening.

Other objects and further scope of applicability of the presentinvention would become apparent from the detailed description to follow.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Polymerizable monomers suitable for use in the present invention includeconventional monofunctional monomers such as acrylonitrile, alkylacrylates and methacrylates, acrylic acid, methacrylic acid, vinylchloride, styrene, olefins such as ethylene and propylene, vinylacetate, etc. However, for the previously noted reasons, polyfunctional,especially trifunctional, monomers are preferred.

The polyfunctional polymerizable monomers of the invention are of thetype conventionally used as cross-linking agents and include, forexample, allylic compounds such as triallyl chloride, allylmethacrylate, diallyl fumarate, triallyl cyanurate or methallylpolyesters, glycidyl methacrylate, diepoxides, divinyl benzene, divinylesters, vinyl crotonate, dicrotonates, divinyl carbinol, diamines andsimilar compounds. The preferred monomers are polyesters having 2 to 4ester groups and at least two independently polymerizable, ethylenicallyunsaturated groups. The term "polyester" includes di-, tri- andtetra-esters of polyhydric alcohols with unsaturated carboxylic acid aswell as polyesters of polybasic acids with unsaturated alcohols. Thepolyester contains at least two carbon-to-carbon double bonds which areseparated by at least one carbon atom and preferably are of thevinylidene type >C═CH₂.

The most preferred monomers used in the present invention are acrylic ormethacrylic acid esters of polyols. Such acrylic and methacrylic estersinclude:

1,4-butylene glycol dimethacrylate;

1,3-butylene glycol dimethacrylate;

1,3-butylene glycol diacrylate;

triethylene glycol diacrylate;

trimethylol propane trimethacrylate;

trimethylol propane triacrylate;

ethylene glycol dimethacrylate;

2-butene-1,4-diol-dimethacrylate;

hexanediol diacrylate;

tetraethylene glycol dimethacrylate;

pentacrylthritol tetra-methacrylate;

glycerol trimethacrylate;

glycerol triacrylate;

trimethylol ethane trimethacrylate;

trimethylol ethane triacrylate; etc.

Typical of such di- and tri-ester acrylic and methacrylic monomers whichare commercially available are CHEMLINK 27A (1,3-butyleneglycoldimethacrylate) and CHEMLINK 30A (trimethylol propane trimethacrylate)marketed by Ware Chemical Company and SARET 500 (trimethylol propanetrimethacrylate) marketed by the Sartomer Company.

As previously noted, the present invention contemplates the addition ofthe aforementioned monomer to an aqueous latex of any synthetic ornatural rubber. Latices of nitrile rubbers, i.e., copolymers ofbutadiene and acrylonitrile, are especially preferred for theabrasion-resistance of the vulcanized products derived therefrom. Thebutadiene:acrylonitrile copolymers ordinarily contain from about 18 to45% by weight of acrylonitrile, the balance being butadiene. Among thecommercially available materials which are suitable for use in thepresent invention are the various copolymers available from the GoodrichChemical Company under the general trade designation HYCAR or fromGoodyear under the general trade designation CHEMIGUM.

Especially preferred for purposes of the present invention are laticesof carboxylated copolymers of butadiene and acrylonitrile. These areproperly considered tripolymers of butadiene, acrylonitrile and acrylicof methacrylic acid. Examples of the commercially available carboxylatednitrile rubber latices are HYCAR 1072 (Bd/ACN=65/34, with 1% carboxylicacid) marketed by B. F. Goodrich and CHEMIGUM NX-775 (Bd/ACN-55/38, with7% carboxylic acid) marketed by the Goodyear Tire and Rubber Company.These carboxylated copolymers contain approximately 0.5-10% by weightterminal carboxyl groups. In the present invention the carboxylatednitrile rubbers are preferred over other nitrile rubbers because thepresence of the carboxylic groups changes the mechanism of the cure in afavorable manner to give a very high gum strength and a tensile strengthon the order of 4000-4500 psi.

To produce the plasticized, non-crosslinked workable compositions of thepresent invention, 5.0-100 parts by weight of the polyfunctionalpolymerizable monomer are added to 100 parts by weight (solids basis) ofthe synthetic or natural rubber latex. A preferred range is 40-60 partsby weight monomer to 100 parts by weight of the elastomeric polymer. Aparticularly preferred ratio for nitrile rubbers is 40 parts by weightmonomer to 100 parts by weight rubber. In the absence of apolymerization initiator no polymerization of the monomer orcrosslinking of the elastomeric polymer occurs and, as a result, thecomposition retains low viscosity and good processibility.

After mixing to obtain a homogeneous admixture in aqueous suspension,the solids, inclusive of the monomer and polymer which have undergone nointerreaction at this point in processing, are coagulated in aconventional manner. For this purpose a rosin acid, fatty acid or saltis added to the latex. A rosin acid is the preferred coagulant forsynthetic rubbers because it imparts tack to the polymer. The coagulatedsolids consisting of the unreated monomer and polymer are then separatedfrom the aqueous phase of the latex and recovered as a homogeneousadmixture. By virtue of the admixing of the monomer and polymer in anaqueous suspension, a high degree of uniformity of distribution of themonomer throughout the polymer is obtained.

The coagulated solids recovered from the latex, including the monomerand the elastomeric polymer, may be washed and dried and are thencompounded with a free radical polymerization initiator which serves notonly as a polymerization initiator for the monomer but also as avulcanizing agent for the rubber. Although it is possible to use anyfree radical producing substance such as barium peroxide, potassiumpersulphate, bis-azoisobutyronitrile, it is preferred to employ organicperoxides such as dicumyl peroxide,benzoyl peroxide, lauroyl peroxide,butyl perbenzoate, that have a half-life greater than 10 hours at thetemperature of mixing and are easily miscible or dispersible in themixture of elastomeric polymer and polyfunctional monomer.

Certain rubbers, such as the butyl rubbers, cannot be vulcanized by freeradical initiators alone. Accordingly, vulcanizable compositions of thepresent invention which contain such rubbers must be compounded not onlywith a free radical producing compound but also with a sulfurvulcanization system. Where a sulfur vulcanization system is necessary,sulfur, a metal oxide (e.g., zinc oxide or zinc peroxide) and avulcanization promoter or accelerator are compounded with thenon-crosslinked vulcanizable composition, along with the free radicalpolymerization initiator. Generally the accelerator is present in thequantity from 0.1 to 30 parts per 100 parts of the elastomeric polymer.Suitable accelerators include inorganic accelerators, such as lime andlead oxide and organic accelerators, such as mercapto-benzothiozole,benzothiazyl disulfide, tetramethyl thiuram monosulfide, zinc dibenzyldithiocarbamate, zinc dibutyl dithiocarbamate, butylaldehyde analine,diphenyl guanidine and diorthotoly guanidine.

Carbon black or non-black inorganic fillers may also be admixed with theunvulcanized compositions of the present invention. The preferrednon-black inorganic fillers include the carbonates such as calciumcarbonate, diatomaceous earth, talc, clays, silicates, silicas,silico-aluminates, the various surface treated or coated clays,carbonates and silicas, and mixtures thereof. Also included in suchfillers are the lubricating or friction-reducing fillers such as theplatey graphites, which may be used alone or in combination withnon-black fillers. Preferably, where a carboxylated Bd/ACN copolymer isto be used for a roll cover, the quantity of filler used is from 0 partsto 200 parts by weight per 100 parts by weight of the monomerplasticized polymer.

Conventional antioxidants are also included in the vulcanizablecompositions, as they are a standard additive in the commercial rubberlatices.

In forming a roll cover in accordance with the present invention theroll core, approximately cleaned and optionally wrapped with a layer offiber or fibrous reinforced resin, is rotated about its axis and theunvulcanized composition, compounded as described above, is extruded asa continuous strip onto the rotating roll surface, for example asdepicted by Hess et al in U.S. Pat. No. 3,698,053. The cover thus formedis then vulcanized under appropriate heat and pressure. During thisvulcanization polymerization of the monomer also occurs.

EXAMPLE 1 (Uncured, Non-Crosslinked Rubber/Monomer Blend)

Two formulations "A" and "B" were prepared as follows:

    ______________________________________                                                         A           B                                                Ingredients      (parts by wt)                                                                             (parts by wt)                                    ______________________________________                                        Bd/ACN Copolymer 100         100                                              (Goodyear N318B                                                               Bd/ACN = 55/45)                                                               Trimethylol Propane                                                                             67          40                                              Trimethacrylate (Monomer)                                                     (CHEMLINK-30)                                                                 Alkylbenzene Sulfonate                                                                         1-1.5       1-1.5                                            Anionic Emulsifier                                                            Water            180         180                                              Antioxidant      1.5         1.5                                              (DIONAX)                                                                      Time             0.5 hrs     0.5 hrs                                          Temperature      50° F.                                                                             50° F.                                    ______________________________________                                    

The latex emulsion was continuously mixed over the half hour periodusing 16 ounces Crown Cap bottles in a shaker. At the end of one-halfhour of TREHNIC, a rosin acid coagulant was added to each formulation.The coagulated solids were then separated from aqueous phase, washed anddried. The dried solids were then tested in a Model ST-1 MooneyViscometer (Scott Tester, Inc.). Formulation A was found to have aMooney viscosity of 27 and formulation B a Mooney viscosity of 57.

EXAMPLE 2 (Uncured, Non-Crosslinked Rubber/Monomer Blend)

The following formulations C, D, E, F, G and H were prepared in a mannersimilar to A and B, above but using a carboxylated copolymer as theelastomeric polymer.

    __________________________________________________________________________    Ingredients                                                                   (parts by wt)    C   D   E   F   G   H                                        __________________________________________________________________________    Carboxylated BN/ACN                                                           Copolymer                                                                     CHEMIGUM NX-775  100 100 100 100 100 100                                      CHEMLINK 30       20  30  0   40  60  0                                       Water            180 180 180 180 180 180                                      DIONAX           1.5 1.5 1.5 1.5 1.5 1.5                                      Time (Hours)     0.5 0.5 0.5 0.5 0.5 0.5                                      Temperature      50° F.                                                                     50° F.                                                                     50° F.                                                                     50° F.                                                                     50° F.                                                                     50° F.                            Mooney Viscosity 50.0                                                                              43.5                                                                              114 44.5                                                                              22.5                                                                              136                                      (ML/4)                                                                        Barbender Heat Stability at 325° F.                                                      13  30  12  24  30  12                                      (100 Meter Torque/gm                                                          Risc min)                                                                     __________________________________________________________________________

As in the preparation of formulations A and B, the emulsion admixtureswere continuously mixed over the half hour period using theaforementioned shaking apparatus. At the end of the half hour period,TRENIC coagulant was added. The dried, coagulant solids were tested in aMooney Viscometer (Scott Tester, Inc.).

In the above formulations, C, D and E employed the same carboxylatedcopolymer. While F, G and H also employed the same CHEMIGUM NX-775, itwas a batch of slightly higher molecular weight than that used for C, Dand E, as reflected by the higher Mooney viscosity for H versus E.

EXAMPLE 3 (Cured Compositions)

The formulations of the above Example were each mixed (in a Scholdmixer) with the following curatives and filler:

    ______________________________________                                         5 parts by weight/100 parts rubber                                                               Zinc Oxide                                                 5 parts by weight/100 parts rubber                                                               DICUP 40 KE                                                                   (40% active Dicumyl                                                           peroxide)                                                 50 parts by weight/100 parts rubber                                                               HISIL 233                                                                     (silica filler)                                           ______________________________________                                    

The admixed formulations were then placed in a mold and cured at 325° F.with the following results:

    __________________________________________________________________________    Cure Data C    D    E    F    G    H                                          __________________________________________________________________________    T.sub.2 Minute                                                                          1.0  0.9  1.75 0.9  0.9  1.6                                        T.sub.90 Minute                                                                         7.5  4.85 15.25                                                                              5.6  9.5  15.5                                       T.sub.95  10.6 7.25 19.5 8.5  5.75 20.0                                       T.sub.max Torque                                                                        148.6                                                                              150.8                                                                              96   142.0                                                                              119.0                                                                              91.5                                                 Cure at 325° F.                                              Minutes   8    5    15   6    10   15                                         Tensile   2200 2200 1200 2700 3500 1400                                       Elong %   90   110  250  60   20   260                                                  Mooney Stability at 158° F. 7 days and 14 days               ML/4 7 days aging                                                                       46   40   120  43   25   --                                         ML/4 14 days aging                                                                      48.5 40   150  45   27   --                                         Uncured Tg °C.                                                                   -28  -33  -21  -35  -41  -18                                        Cured Tg °C.                                                                     -13  -21  -16  -15  -15  -18                                        __________________________________________________________________________

EXAMPLE 4

This example was designed to compare the wet-blending technique of thepresent invention with the conventional prior art dry-blendingtechnique. The following two formulations were blended in a ScholdMixer:

    ______________________________________                                                                        J                                                               I             (prior                                        Ingredients (pts by wt)                                                                         (present invention)                                                                         art)                                          ______________________________________                                        Monomer/Elastomer 140           --                                            Blend "F" of Example 2                                                        Rubber (CHEMIGUM NX-775)                                                                        --            100                                           Monomer (CHEMLINK 30)                                                                           4             44                                            Zinc Oxide        5             5                                             Antioxidant (FLECTOL H)                                                                         3             3                                             Stearic Acid      1             1                                             FEF Carbon Black  40            40                                            Dicumyl Peroxide  2.5           2.5                                           Wax               3.0           3.0                                           Bismelamide       2.0           2.0                                           Silane Treated Clay                                                                             40.0          40.0                                          ______________________________________                                    

The curing characteristics and properties were as follows:

    ______________________________________                                                      I          J                                                    ______________________________________                                        Hardness (P & J)                                                              90' at 306° F.                                                                         6            7                                                180' at 306° F.                                                                        6            6                                                Mooney Scorch at 275° F.                                               T.sub.5         3.6          6.4                                              Min. Viscosity  27           12                                               Rheometer at 280° F.                                                   T.sub.2         5.5          6                                                T.sub.90        23           29                                               Min. Torque     5            2                                                Max. Torque     87           84                                               Stress-Strain 0°                                                       Test Orientation                                                              Tensile Strength (psi)                                                                        4300         3900                                             % Elongation    19           20                                               Stress-Strain 90°                                                      Test Orientation                                                              Tensile Strength (psi)                                                                        4600         4000                                             % Elongation    17           19                                               ______________________________________                                        Dynamic Properties                                                            (600 psi Stress)                                                                              Vol.             Vol.                                         Temp °F. Hyst.   Dyn. E   Hyst.                                                                              Dyn. E                                  ______________________________________                                         80             1.57    106060   2.44 95140                                   100             1.87    91930    2.57 79930                                   150             2.73    63360    3.92 54100                                   200             3.94    44420    4.85 38730                                   250             5.61    32110    6.61 28470                                   300             7.48    24320    8.41 22310                                   ______________________________________                                        (800 psi Stress)                                                               80             2.69    108710   3.79 93900                                   100             3.23    93640    4.47 79300                                   150             5.17    61110    7.12 52230                                   200             7.32    43710    9.77 37110                                   250             10.36   31250    12.20                                                                              27900                                   300             13.52   24300    15.44                                                                              22090                                   ______________________________________                                        (1000 psi Stress)                                                              80             4.12    110210   6.46 90100                                   100             4.86    93550    7.42 79720                                   150             7.98    61230    9.19 53900                                   200             11.42   43820    14.15                                                                              36880                                   250             17.44   29480    19.46                                                                              28010                                   300             24.62   22660    24.53                                                                              22310                                   ______________________________________                                        Hydrolytic Stability                                                          (7 days at 212° F. Tap Water)                                          % Weight Increase                                                                             3.06         2.0                                              % Volume Increase                                                                             3.22         1.92                                             Hardness Change (P & J)                                                                       +3           +2                                               ______________________________________                                        Solvent Stability                                                             (7 days at 158° F. Kerosene/Water 50/50)                               % Weight Increase                                                                             2.84         3.40                                             % Volume Increase                                                                             3.66         4.53                                             Hardness Change (P & J)                                                                       +5           +6                                               ______________________________________                                        Hardness Stability (P & J)                                                    Hardness at RF  8            8                                                100° F.  10           10                                               125° F.  12           12                                               150° F.  14           14                                               175° F.  15           14                                               200° F.  15           14                                               225° F.  15           14                                               250° F.  15           15                                               Δ(P & J)  +7           +7                                               ______________________________________                                    

In the Pico abrasion test compositions I and J showed a % relative indexof 322 and 245, respectively. Thus, composition I was found to have asignificantly higher abrasion resistance.

The invention may be embodied in other specific forms without departingfrom the spirit or essential characteristics thereof. The foregoingembodiments are therefore to be considered in all respects asillustrative and not restrictive, the scope of the invention beingindicated by the appended claims rather than by the foregoingdescription, and all changes which come within the meaning and range ofequivalency of the claims are therefore intended to be embraced therein.

I claim:
 1. A method for producing a non-crosslinked vulcanizableelastomeric composition comprising:providing 100 parts by weight, solidsbasis, of a latex of an elastomeric polymer; adding to and admixing withsaid latex 0.5-200 parts by weight of a polymerizable monomer;coagulating the solids in said latex including said monomer and saidelastomeric polymer, said admixing and coagulating being effected in theabsence of a polymerization initiator for the monomer with substantiallyno polymerization of said monomer and substantially no crosslinking ofor grafting onto said elastomeric polymer; and separating saidcoagulated solids from the liquid phase as the elastomeric compositionin the form of a homogeneous admixture of said polymer and said monomerfree of any polymerization initiator for the monomer.
 2. The process ofclaim 1 wherein the weight ratio of monomer to polymer is within therange of 2:5 to 1:2.
 3. The process of claim 1 or 2 wherein saidpolymeric elastomer is a copolymer of butadiene and acrylonitrile andsaid monomer is a polyfunctional monomer.
 4. The process of claim 1 or 2wherein said polymeric elastomer is a carboxylated copolymer ofbutadiene and acrylonitrile.
 5. The process of claim 3 wherein saidpolyfunctional monomer is an acrylic or methacrylic ester of a polyol.6. The process of claim 4 wherein said polyfunctional monomer is anacrylic or methacrylic ester of a polyol.
 7. A monomer-plasticized,non-crosslinked, elastomer composition in the form of a homogeneousadmixture consisting essentially of an elastomeric polymer and apolymerizable monomer, free of filler, and produced by adding andadmixing 5.0-200 parts by weight of said polymerizable monomer and 100parts by weight, solids basis, of a latex of said elastomeric polymer,coagulating said latex and separating the coagulated solids to recoversame as said elastomeric composition, said admixing and coagulatingbeing effected in the absence of a polymerization initiator for themonomer with substantially no polymerization of said monomer andsubstantially no crosslinking of or grafting onto said elastomericpolymer.
 8. The elastomer composition of claim 7 wherein the weightratio of said monomer to said polymer is within the range of 2:5 to 1:2.9. The elastomeric composition of claim 7 wherein said polymer is acopolymer of butadiene and acrylonitrile.
 10. The elastomericcomposition of claim 7 wherein said polymer is a carboxylated copolymerof butadiene and acrylonitrile.
 11. The elastomeric composition of claim9 or 10 wherein said monomer is an acrylic or methacrylic acid ester ofa polyol.
 12. A non-crosslinked elastomeric composition in the form of ahomogeneous admixture consisting essentially of an elastomeric polymerand a polymerizable monomer, free of filler, and produced by admixing0.5-200 parts by weight of said polymerizable monomer and 100 parts byweight, solids basis, of a latex of said elastomeric polymer,coagulating said latex and separating the coagulated solids to recoversame as said elastomeric composition, said admixing and coagulatingbeing effected with substantially no polymerization of said monomer andsubstantially no crosslinking of or grafting onto said elastomericpolymer.
 13. The method of claim 1 wherein said polymerizable monomer isa polyfunctional monomer.
 14. The method of claim 1 wherein saidpolymerizable monomer is a trifunctional monomer.
 15. The composition ofclaim 7 wherein said polymerizable monomer is a polyfunctional monomer.16. The composition of claim 15 wherein said polyfunctional monomer is atrifunctional monomer.
 17. The process of claim 1 wherein saidelastomeric polymer is of butadiene and acrylonitrile having terminalcarboxyl groups.
 18. A method according to claim 1 wherein at least 5parts by weight of said monomer are added to said latex, therebyplasticizing the elastomeric composition.